正数和与积的对偶不等式

给出了在个数相同的两组正数之积相等的情形下,判定这两组正数之和大小的一个充分条件,由此得出了正数和最大值存在的链式条件．应用这一链式条件解决了将,nl个正数分成等个数的n个数组后,每组之积的和与每组之和的积的最值问题．对于正数积的最小值问题,证明了与正数和最大值类似的结果,且相应的定理之间互为对偶定理．     

用于3D模型检索的扩展距离球面调和表达

使用光线投射方法对3D模型定义了一个对应的球函数--扩展距离球函数,然后引入了球面调和分析方法,构造了一种对于平移、缩放和旋转变换具有不变性的特征向量,并用于基于形状的3D模型检索中.与基于向径方法结合,提高了检索的效果,扩大了应用范围.     

炼化企业生产计划优化软件RPMS的应用研究

首先介绍了炼化企业的计划制定流程，并对国内计划优化软件的使用进行了分析总结；对RPMS软件的功能进行了说明，并对软件内部数据进行了分析。通过进行案例分析对RPMS软件在计划优化方面的功能进行研究说明，得出RPMS软件是完全能够满足国内炼化企业生产计划优化的需求。能够在日益激烈的国际市场竞争中提升企业的市场竞争力和企业的经济效益。     

一个新的最大流问题增载轨算法

通过放松Ahujia和Orlin算法的约束，给出了一个新的增载轨算法．该算法实质上提供了一个构造、阻塞无环网络的策略，它可以在每次构造无环网络中得到更多的增载轨．从而进一步降低了找到每条增载轨的代价．实验表明，新的算法比Dinic算法快2～5倍，和目前实验性能最好的预流推进算法基本相近．说明增载轨类算法在实际性能方面未必落后于预流推进类算法．     

Classical Approach to Analyzing the Influence of Edge Boundary Conditions on Stresses and Flexibility of Pipe Elastic Bend

A new analytical method is proposed for the analysis of boundary effect in a pipe bend portion loaded by bending moment combined with internal pressure. The proposed method is based on the simplifying hypotheses, which make possible to represent all deformation- and force-related parameters in terms of the tangential displacement assumed in the form of the Fourier series expansion by the circumferential coordinate. A set of quadric differential equations by axial coordinate containing unknown displacement expansion coefficients is derived. We obtained an analytical approximate solution for a pipe bend portion and precise solution for a straight pipe, which are expressed via Krylov functions. We formulate the application procedure for the method of initial parameter, where the values of tangential and longitudinal displacements, axial and tangential forces are used as boundary conditions. We present the equations relating the above-mentioned parameters in the initial and end sections of the pipe bend portion. The results obtained are compared with the available published data. __________ Translated from Problemy Prochnosti, No. 4, pp. 64 – 94, July – August, 2005.     

A bending specimen for constant energy release rate under controlled displacement conditions

A bending specimen that gives a constant energy release rate (independent on the crack length) under controlled displacement conditions is developed. It is assumed that engineering beam theory is applicable, i.e. that among other things, small deformations and linear elastic isotropic material can be assumed.A specific geometry is analyzed numerically by use of the finite element method and experimentally by manufacturing a specimen with the actual geometry in PMMA (polymethylmetacrylate) and then determining the specimen stiffness for different crack lengths.It is found that the geometry considered gives a constant energy release rate under controlled displacement conditions.     

提高容栅位移传感器精度的有效方法

为解决环境温度变化、尺体导轨加工误差以及边缘效应等因素对容栅位移传感器测量精度的影响,提出了三极板结构、周期比较测量以及分段采用正余弦极板分段数据处理的方案。三极板结构中动极板仅起屏蔽作用,可以降低对尺体导轨加工精度的要求;周期比较测量在提高系统温度稳定性的同时,由于采用了全数字电路的实现方式能有效降低专用集成电路的设计、制作成本;交替使用正余弦极板的读数避开边缘效应的影响。理论分析和实验结果证明了该方案的可行性。     

电位器式位移传感器负载特性的自动补偿

研究了用通用集成运算放大器和正电压可调集成三端稳压器实现电位器式位移传感器负载特性非线性自动补偿的方法。该方法既较好地补偿了电位器式位移传感器负载特性的非线性,又很好地解决了电位器式位移传感器负载能力弱的问题。测试表明:该方法补偿效果好,具有实用性。     

Optimization of practical trusses with constraints on eigenfrequencies, displacements, stresses, and buckling

In this paper we consider the optimization of general 3D truss structures. The design variables are the cross-sections of the truss bars together with the joint coordinates, and are considered to be continuous variables. Using these design variables we simultaneously carry out size optimization (areas) and shape optimization (joint positions). Topology optimization (removal and introduction of bars) is only considered in the sense that bars of minimum cross-sectional area will have a negligible influence on the performance of the structure. The structures are subjected to multiple load cases and the objective of the optimizations is minimum mass with constraints on (possibly multiple) eigenfrequencies, displacements, and stresses. For the case of stress constraints, we deal differently with tensile and compressive stresses, for which we control buckling on the element level. The stress constraints are imposed in correlation with industrial standards, to make the optimized designs valuable from a practical point of view. The optimization problem is solved using SLP (Sequential Linear Programming).     

Solving a Nonlinear Problem in Magneto-Rheological Fluids Using the Immersed Interface Method

Many applications lead to a nonlinear elliptic interface problem in which the discontinuous coefficient depends on the solution and the material properties. A finite difference method based on Cartesian grids and the maximum principle preserving immersed interface method is proposed for the nonlinear elliptic interface problems discussed in this paper. Numerical experiments against the exact solutions reveal that our method is nearly second order accurate in the infinity norm. The method is applied to study the magneto-rheological field-responsive fluids that contain iron particles. Numerical experiments are performed against the results from the literature.